A good used Jaguar MK2 Salisbury axle 4HA crown wheel and pinion ratio 4.27:1 Jaguar part number 6309 or 4HA-105/12A as fitted to automatic or std transmission on the MK2 also fitted to the 3 XK's
Good used condition as you can see from the pictures and if you're going to fit to your classic I'd recommend fitting new bearings on the pinion.

Sorry about the high postage costs but it's the insurance that kills it!!